Apparatus for grinding, mixing, and kneading materials



G. A. VASEL 2,509,379 mm-us FOR GRINDING, urxmc,

ALS

May 30, 1950 AND mums MATERI 2 Sheets-Sheet 1 Filed June 24, 1948 I M om W 1/ o E W m fl Q Y w W 3 mm 3 am. Aw @N #0 U2 .II II MN I I n Q s 8=2 3 NM 5 mm .8 T M &m n v .v mm Rm 0 a Wm. N. a Lt y 1950 7 G. A. VASEL2,509,379

APPARATUS FOR GRINDING, uzxmc, AND mums MATERIALS Filed June 24, 1948 2Sheets-Sheet 2 INVENTOR 6:15?! A. Vusel WMW% ATTQRNEYJ chanted y 15 idAPPARATUS FOR GRINDING, MIXING, AND KNEADING MATERIALS Gustav A. Vase],Elkins Park, Pa.

Application June 24, 1948, Serial No. 34,865

Claims.

This invention relates to methods and apparatus for mixing wet and drymaterials such as a liquid vehicle and solids such as pigments, etc.,and has for an object the provision of a system and apparatus forproducing a combined grinding, kneading and mixing action of highefficiency for an end product of great uniformity.

The invention has been found particularly applicable to the dispersionof a pigment into a vehicle to produce materials such as paints andinks; and to the dispersion and mixing of foodstuffs such as margarin,peanut butter, etc. Heretofore, adequate mixing and grinding of suchproducts has involved several independent operations and considerablecomplex equipment. For example, preparation of paint has required theuse oi several pieces of apparatus which are heavy, bulky and expensive.Pigment received in dry form was delivered to dough mixers where the drymaterial was put into the vehicle and mechanically stirred until theparticles were considered adequately wetted. The mass was then deliveredto grinding mechanism such as roller mills. Thereafter, the mixturepassed through a homogenizer or again through the dough mixer. Theentire operation was relatively lengthy, from ten to ninety hours beingrequired for adequate treatment in a ball mill or roller mill.

In carrying out the present invention in one form thereof, a mixture ofdry material, together with liquid material such as one or morevehicles, is introduced into a zone wherein there is a grinding,kneading and mixing action along a spiral path with forcible ejection ofthe material from the mixing zone. More particularly, the mixture is fedbetween a pair of blades or idlers each having a. spiral thread thereonmeshing with spiral threads on a centrally disposed rotor. Thecomplementary threads are preferably provided so that the material isground between contacting portions and, at the same time, kneaded forthoroughdispersion of the material. Flow-producing means beyond themixing area driven by the rotor and having a controlled or predeterminedcapacity receives the ejected maserial and conveys it away at apredetermined rate to control the pressure effective in the mixing area.There is a reduction of agglomerates and aggregates which meansreduction in par ticle size so that in the end product there is amaximum degree of fineness. The combined wiping, rubbing and grindingaction results in a homogeneous mixture as the end product.

For further objects and advantages of the invention, reference is to behad to the accompanying drawings in which:

Fig. 1 is in part a sectional view of an apparatus embodying theinvention;

Fig. 2 is a section taken on the line 2-2 of Fi Fig. 3 is a sectiontaken on the line Fig. 1;

Fig. 4 is a section taken on the line l-l of Fig. 1; and

Fig. 5 is a section taken on the line 5-5 of Fig. 1, with certain partsomitted.

Referring to the drawings, the invention in one form has been shownapplied to a grinding, kneading and mixing apparatus in which materialis fed from a hopper I I] through an inlet opening II of a casing orhousing I2. The material flows into the mixing area between a pair ofblades I3 and I4 disposed in openings I5 and I 8 spaced radially outwardfrom a central cylindrical opening I'I having disposed therein a centralrotor I 8. Similar blades I9 and 20 are provided in radially spacedopenings ZI and 22. The five openings I5, I6, I1, 2| and 22 are allcylindrical and extend substantially the full length of the casing I2.The rotor and each of the blades closely fits its cylindrical opening.Each blade meshes with and is complementary to the rotor I8 disposedwithin the central opening H. The rotor I8 is provided with an extensionI8a having on the end thereof a gear 23 meshing with a driving gear 24carried by the shaft of a motor 25. A packed bearing 26 is provided forextension I811, while at the opposite end of the rotor I8 a bearingplate 21 is provided. The bearing plate 21 has a reentrant opening 21ainto which the end of rotor I8 extends, a shoulder I8b being provided toabut a complementary shoulder of the plate 21. A portion I of the rotorI8 of reduced diameter extends to the face of the plate 21 and is therefurther reduced in diameter and threaded at I8d to receive theflow-producing propeller I Be. The rotor end portion I80 is of suchlength that the rotor I8 may turn freely but is retained in fixed axialrelation with member when the propeller I8e is screwed tightly againstthe shoulder at the end of the threaded portion I8d. The plate 21 thenreceives axial forces from the rotor through the propeller I8e.

The helical member on rotor I8 may be a single righthand thread or bladeof relatively large pitch. It meshes with cooperating threads on theblades I3, I4, I9 and 20. The axial length of the blade on rotor I8 isconsiderably less than the axial length of blades l3, I4, [9, and 20. Asviewed in Fig. 4, the direction of rotation of rotor I8 is clockwise,thus forcing the mixed material from the grinding-mixing area into thechamber IZb. Each blade driven by rotor I8 abuts against the bearingplate 21. As indicated, the plate 21 (of any suitable bearing materialsuch as bronze) is provided with a plurality of openings 2117, Fig. 3,angularly disposed intermediate the radially spaced blades for exit ofmaterial into an outlet chamber 33 and thence to an outlet system (shownin Fig. 1', reduced in scale beyond chamber The plate 27 is held inplaceby the housing 63 for chamber 35 which is secured to the casing 52 by aplurality of bolts 44.

The propeller i8e positioned adjacent the plate Eland in chamber 3|preferably is of such dimension and configuration that it has greaterfluid-moving capacity than the rotor l8 and blades i3, i4, i9 and 20. Insuch preferred form the mixture is removedtfrom the chamber l2b so thatrotor 18 and its complementary blades will not be required to operateunder back pressure. As a result, the rotor and blades run relativelyfree, thus eliminating friction heating of the device and the mixtureoccasioned by grinding and mixing at elevated pressures. Such heating isobjectionable in mixing of certain products.

In other operations, the back pressure may be controlled by properselection of the size and configuration of the propeller [8a. In anyevent, the pressure in the working area may be controlled and at thesame time an output pressure maintained to convey the mixture to thesite of further operations (packaging, etc.) without the need ofadditional pumping or conveying equipment.

The thread or blade on rotor l8 and the pitch of the propeller areopposite in sense to the threads on the end l8d of the rotor 18. Theforce created by working against the mixture serves tightly to screw thepropeller onto the end of the rotor to maintain the fixed axialrelationship with respect to the bearing plate 21.

The pressure in the output is indicated by a pressure gage 36. Themixing may be at elevated temperatures, ii? desired, and under anysuitable control as indicated by a contact-making thermometer 31 whichmakes and breaks energizing circuits for relay apparatus 38 for controlof the energization of a heater coil 39 connected to supply lines 40.Under similar control, a fluid may be circulated in a heat-transfersystem associated with the device either to increase or decrease thetemperature of the material independent of the working pressure.

It is desirable in certain applications to recycle a fraction of thematerial being mixed, and

for this purpose a return line 4| having a control valve 42 may beutilized. By partially closing the valve 34 to increase the pressurebehind it, material may be made to flow through line 4| and into thehopper I0.

The apparatus as a whole is of relatively low cost, simple in operationand yet produces combined grinding, mixing, kneading and dispersingactions which rapidly and efliciently produce an intimate mixture ofsolid materials with liquid materials. The system is such that productsmay be mixed in the single apparatus and in accordance with the processabove described without need for preliminary treatment in ball mills,homogenizers and the like. The invention is applicable to a plurality ofmaterials, particularly where there is product-appreciation orenhancement of value of the product by reason of the intimacy of themixture of the solid materials with the liquid components.

While four blades or spirally-threaded grinding elements driven by therotor have been disclosed, it is to be understood that advantages .willbe secured with systems using two or more such blades where theirorientation about the rotor is such that the radial forces on the rotorare substantially balanced to permit relatively high speed operation.

The material to be mixed or ground may be moved from the hopper [0, asby gravity, or if desired by spiral feed means. It enters the mixer inan open free space which extends between the two upper blades l3 and I4,and enters into the grooves between the threads thereof. It is divided,a part being pushed along each of the grooves, but each part joining anduniting with the other as the groove intersects the threaded centrallylocated member I8. The mixture is ground between metallic surfacesinsliding engagement. The driving member I8 tends to move to the left andthe driven blades to the right. The plate 21 restrains axial movement ofthe rotor and blades thereby causing considerable force to be exerted onthe contact faces of the thread and grooves. Grinding action takes placebetween the contact faces of the spiral thread on the central rotorblade [8 and complementary spiral grooves on the blades I3, I 4, l9 and20.

The cylindrical openings l5, 16, 2| and 22 are so disposed with respectto the central opening I8 that considerable rolling action takes placebetween the crest of each of the outer blades and the axial spacebetween the spiral thread on the central blade 18. Additional grindingand wiping action takes placebetween the crests of each of the outerblades and the walls of their respective chambers. The mixing, kneading,wiping and grinding action continues throughout the length of the casingII. The flow of the mixture from the grinding area is controlled bypropeller Ille, thus the pressure in the reentrantopening I2b, throughwhich the radially spaced blades extend, also is controlled.

The apparatus is relatively small in size, compact, and is of but fewmoving parts. By way of example, in one modification of the mixer thehousing was approximately 4" square and 12" long; the central openingapproximately 1.75 in diameter, and the blades, 1" in diameter. The,rotor was driven at a speed of 3600 R. P. M. by a motor of 7.5 H. P.

It is emphasized that not only is there provided, in accordance with thepresent invention, a new form of mixing device, but also in accordancewith the method and the mode of operation of the new device there isproduct improvement due to the more complete dispersion of the solidmaterials and the liquid materials. By locating the idlers or, blades I3 and [4 on oposite sides of the inlet II, the material to be treateddivides between the two spiral channels and moves forward in dividedspiral paths which, because intersecting with the central drive roller,again divides and is distributed circumferentially of the mixer. Thereis avoided direct travel of the material along single spirals. Instead,the material divides among the spirals and is rotated around the centraldriving rotor and is constantly sub-divided between the driven blades.

Where the kneading and mixing and dispersing actions are to be conductedunder a minimum of pressure, the propeller l8e performs the importantfunction of moving the material forward through the outlet with aresultant reduction of pressure on the material as it passes through thespiral rotor and cooperating blades.

process may, therefore, be conducted at lower temperatures without theprovision of additional cooling means which, as previously noted, can besubstituted for the heater 39 shown in Fig. l.

The propeller l8e rotating in the discharge chamber performs theadditional function of added mixing by reason of its rotation throughthe mass as it is discharged from the driving rotor and the cooperatingblades. The pitch of the blades of the propeller assists in moving thematerial forward (though in special cases the pitch could be reversed),the resultant thrust from the propeller makes it possible to eliminateball bearings. This means that cleaning is greatly facilitated which isnot only particularly important with reference to food products, but isan advantage from the standpoint of economy and time devoted to cleaningthe device when used in any mixing operation. The bearing plate 21,neutralizing all axial forces in the system, is of reasonably simpleshape, and yet performs a plurality of functions. It maintains theidlers or mixing blades in place and takes the thrust of the drivingrotor by way of the hub of the propeller I Be which is threaded on theend of the rotor i8 and disposed in abutting relation with the centralpart of the plate 21. Finally, the particular arrangement of drivingrotor and mixing blades results in a relatively fast movement of thematerials in circumferential and axiallyspiraling paths in which thereis substantial turbulence created for most efficient mixing without theinduction of air due to the turbulence occurring within the mixingcylinders in which the spiral elements are disposed. Induction of air isalso lacking in the discharge chamber in which the propeller l8e isdisposed, since the material fills the discharge chamber completely.

While a preferred form of the invention has been illustrated, it is tobe understood that modifications may be made within the scope of theappended claims.

What is claimed is:

1. In a continuous mixer a casing having four elongated chambersextending radially from and parallel to a central chamber, spiral bladesin each of said four chambers, a rotor in said central chamber meshingwith each of said blades, driving means for rotating said rotor and saidblades, said casing having an opening intermediate a pair of said bladesfor feeding material thereinto for divided spiral flow, said casingbeing provided with an exit axially extending from said blades, abearing plate disposed at said exit having openings therein and, bearingportions on one side thereof engaging said rotor and said blades, andfluid-moving means secured to said rotor and bearing on a side of saidplate opposite said bearing portions to maintain in axially fixedposition said rotor and said blades.

2. A continuous mixer comprising a casing having a central chamber, aspiral rotor extending through the length of said chamber, means fordriving said rotor, a plurality of openings radially spaced from saidcentral chamber/a spiral blade within each of said radially spacedopenings and meshing with said centrally disposed rotor, said casinghaving an inlet for flow of material thereinto, a bearing plate disposedat one end of said central chamber having openings therein for dischargeof material after it has been subjected to a Wiping and rubbing actionby said meshing blades, a propeller to receive and move said materialsaway from said rotor and said blades, said propeller having greaterfluidmoving capacity than said rotor and said blades, and meanscontrolling the temperature of said mixer independent of the workingpressure.

3. Apparatus for milling and mixing the combination of wet and drymaterials which comprises a rotor with a helical thread of relativelylarge pitch, a thrust plate, one end of said rotor extending throughsaid thrust plate, fluidmoving means fastened to the extended end ofsaid rotor and adjacent said thrust plate, means for driving said rotor,said fluid-moving means bearing against one side of said thrust plate totransmit thereto the axial thrust developed upon rotation of said rotor,a plurality of threaded idlers symmetrically disposed about and held inmesh with said rotor abutting said thrust plate and neutralizing saidaxial thrust on said rotor, means for introducing said materials intosaid apparatus at the end opposite said thrust plate,

and a flow channel for receiving said material the rotor, idlerssymmetrically disposed about said driven rotor meshing with saidintermediate portion and driven thereby, said idlers bearing against oneside of said thrust plate and in cooperation with said rotor millingsaid-mixture while conveying it toward said thrust plate, a propellerthreaded on the extended end of said rotor and bearing against anopposite side of said thrust plate to thus neutralize axial forcesdeveloped when said material is introduced into said apparatus, saidpropeller having a predetermined capacity with respect to the capacityof said idlers and said rotor thereby to control the back pressure onsaid material in the grinding and milling operation.

5. In an apparatus for producing uniform dispersion of a mixture ofliquids and solids com prising a rotor having threads of relativelylarge pitch throughout afcentral portion thereof and an end threadedwith the pitch opposite to that of said central portion, a housinghaving a central cylinder within which said rotor is disposed. saidhousing having a plurality of .cylinders intersecting with said centralcylinder, idlers disposed within each of said intersecting cylinders andeach having threaded central portions meshing with said intermediateportion of said rotor, said housing having a discharge chamber forreceiving material discharged from said rotor and its idlers, a thrustplate within said discharge chamber having openings for discharge ofmaterial therethrough and having a hub portion engaging a shoulder onsaid rotor and having bearing surfaces engaging the ends of said idlers,means threaded to said end of said rotor for en gaging said thrust plateon the side remote from said shoulder whereby axial forces developed bysaid rotor and said idlers tend to neutralize each other by applyingsaid axial forces oppositely to said thrust plate, means for rotatingsaid rotor and said idlers for forced flow of said mixture through eachspiral path formed between said threaded portions and its associatedcylinder, said forced flow developing a grinding and keading actionunder a gradually increasing pressure axially of said cylinders, and apropeller driven by said rotor within said discharge chamber having thepitch of the blades thereof in a direction to assist movement of saidmixture away from said cylinders thereby to reduce the pressure withinsaid cylinders.

GUSTAV A. VASEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

8 UNITED STATES PATENTS Number Name Date La Casse Oct. 19, 1920 HottmanMay 16, 1922 Oflenhauser Mar. 18, 1930 Ostermann Nov. 1, 1932 AlstadApr. 9, 1935 Wells Sept. 29, 1936 Thalman Sept. 14, 1937 Halstrup Aug.22, 1939 Labour June 29, 1943 Marshall Jan. 20, 1948

